This invention relates to an improvement in a rotary apparatus of a die unit for manufacturing a core lamination assembly, and more particularly to a rotary apparatus of a successive feed die unit to collectively transmit intermittent rotation and other skew angle rotation to a lower rotatable die of the die unit.
In a conventional die unit for manufacturing a core lamination assembly for a motor of dynamoelectric machine components, a metal strip is stamped by a successive feed die unit, and predetermined numbers of the stamped core metal strips are stacked. However, lamination of the metal strips is not perfect because of variations in the thickness of each portion of the products due to the deflection of the thickness of metal strips which occurs during rolling. Accordingly, the parallel degree of upper and lower surfaces and the accuracy of the outside and inside diameters are deteriorated.
Therefore, in the past, countermeasures for removing the deflection of the thickness have included a method of rotating the metal strip or strips when the metal strips are stamped, by a predetermined angle of 90 or 180 degrees, as proposed in Japanese Patent Application Publications Nos. 43276/1972 and 18044/1976.
And, it is also known that the metal strip for lamination is rotated at a predetermined minute angle, e.g. a strip is skewed for elevating the electric characteristic in Japanese Utility Model Application Publication Nos. 53183/1978, 36137/1984 and 25318/1985. In Publication No. 36137/1984, it is disclosed that the metal strips are skewed by a step-motor. In this way, it is possible to stack by rotating lamination and simultaneous skewing thereof, but the control is very complicated and the proposed method is not practical.
In the conventional techniques stated above, the rotating lamination and skewing are carried out separately. Therefore, the both functions are not simultaneously completed, particularly, it is impossible to improve the efficiency of the products, since only one function is available in manufacture of a rotor for the motor of the dynamoelectric machine due to the method of progressive stamping and stacking of the metal strips in the conventional die.
Recently, a die apparatus has been proposed in Japanese Patent Application Laid Open No. 170534/1985. This apparatus has gear means between an indexing apparatus for input of rotation of a crank shaft of a press apparatus, and a rotatable die of a die unit, and it is available to simultaneously carry out rotational lamination and skewing of the metal strips. But, this apparatus cannot change skewing volume without steps, since the apparatus uses the gear apparatus, and the skew volume is limited due to the number of the teeth of the gear apparatus. Therefore, in practical use, there is a problem that the most desirable skewing volume is not given to carry the best electric characteristic and provide high precision in deflection of the outside and inside diameters of the products.